Browsing by Author "Baffoe-Wilmot, A."
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Item Evaluation of piperonyl butoxide in enhancing the efficacy of pyrethroid insecticides against resistant Anopheles gambiae s.l. in Ghana(Malaria Journal, 2017) Dadzie, S.K.; Chabi, J.; Asafu-Adjaye, A.; Owusu-Akrofi, O.; Baffoe-Wilmot, A.; Malm, K.; Bart-Plange, C.; Coleman, S.; Appawu, M.A.; Boakye, D.A.Background: Malaria vector control methods involving the use of pyrethroids remain the strategies being used against malaria vectors in Ghana. These methods include the use of long-lasting insecticidal nets and indoor residual spraying in many areas in Ghana. However, there is evidence that pyrethroid resistance is widespread in many areas in Ghana. Synergists have been shown to be useful in inhibiting the enzymes that are responsible for the development of resistance and hence enhance the insecticide susceptibility of Anopheles gambiae sensu lato (s.l.) in many areas. The present study investigated the effect of piperonyl butoxide (PBO) on the susceptibility status of An. gambiae s.l. across some sentinel sites in Ghana. Methods: Three to five day old An. gambiae s.l. reared from larvae were used in WHO susceptibility tube assays. Batches of 20-25 female adult An. gambiae s.l. were exposed simultaneously to the insecticide alone and to the PBO + insecticide. The knock down rate after 60 min and mortality at 24 h were recorded. Results: Deltamethrin and permethrin resistance of An. gambiae s.l. was observed in all the sites in 2015 and 2016. The mortality after 24 h post exposure for deltamethrin ranged from 16.3% in Weija to 82.3% in Kade, whereas that for permethrin ranged from 3.8% in Gomoa Obuasi to 91.3% in Prestea. A significant increase in susceptibility to deltamethrin and less to permethrin was observed during both 2015 and 2016 years in most of the sites when An. gambiae s.l. mosquitoes were pre-exposed to PBO. Conclusion: Findings from this study showed that the use of PBO significantly enhanced the susceptibility of An. gambiae s.l. mosquitoes in most of the sentinel sites. It is recommended that vector control strategies incorporating PBO as a synergist can be effective in killing mosquitoes in the presence of deltamethrin and permethrin resistance. © 2017 The Author(s).Item Lymphatic filariasis in Ghana: Entomological investigation of transmission dynamics and intensity in communities served by irrigation systems in the Upper East Region of Ghana(Tropical Medicine and International Health, 2001-07) Appawu, M.A.; Dadzie, S.K.; Baffoe-Wilmot, A.; Wilson, M.D.We conducted an entomological study to document the effect of irrigation on the vectors and transmission dynamics of lymphatic filariasis in the Upper East Region of Ghana. Mosquitoes were collected by indoor spraying of houses in a cluster of communities located around irrigation projects (Tono and Vea) and others without reservoirs (Azoka). Anopheles gambiae s.s. was the dominant species and major vector, followed by An. funestus. Anopheles arabiensis constituted 9-14% of the An. gambiae complex but none were infective. Culex quinquefasciatus was also not infective in these communities. Chromosomal examinations showed that >60% (n = 280-386) of the An. gambiae s.s. in irrigated communities were Mopti forms whilst 73% (n = 224) in the non-irrigated area were Savannah forms. Infectivity rates (2.3-2.8 vs. 0.25), worm load (1.62-2.04 vs. 1.0), annual bites per person (6.50-8.83 vs. 0.47) and annual transmission potential (13.26-14.30 vs. 0.47) were significantly higher in irrigated communities.Item Lymphatic filariasis in Ghana: Establishing the potential for an urban cycle of transmission(Tropical Medicine and international Health, 2005) Gbakima, A.A.; Appawu, M.A.; Dadzie, S.; Karikari, C.; Sackey, S.O.; Baffoe-Wilmot, A.; Scott, A.L.Lymphatic filariasis is a significant public health and economic problem in many tropical and subtropical regions. Unplanned urbanization leading to a lack of proper sanitary conditions has resulted in an increase in the urban-based transmission of a number of vector-borne diseases, including lymphatic filariasis. It has been well established that lymphatic filariasis is endemic in rural areas of Ghana. The goal of this study was to determine if there is a potential of establishing urban transmission cycles in Ghana's major cities. We clinically and immunologically assessed 625 individuals from the three major urban areas (Bawku, Bolgatanga and Secondi/Takoradi), finding that the prevalence of infection with Wuchereria bancrofti ranged from 0 to 12.5%. The results of a polymerase chain reaction based analysis of mosquitoes collected from these areas suggested that there is a low but detectable prevalence of mosquitoes infected with W. bancrofti. We conclude that there may be a potential for an established urban transmission of lymphatic filariasis in Ghana. © 2005 Blackwell Publishing Ltd.Item Lymphatic filariasis on the coast of Ghana.(Transactions of the Royal Society of Tropical Medicine and Hygiene, 1996) Dunyo, S.K.; Appawu, M.; Nkrumah, F.K.; Baffoe-Wilmot, A.; Pedersen, E.M.; Simonsen, P.E.Parasitological, clinical and entomological surveys for lymphatic filariasis were carried out in 6 villages and 3 towns on the coast of Ghana. Few or no filarial infections were observed in the towns or in the villages east of Accra. However, Wuchereria bancrofti microfilaraemia was common in the 4 western villages, with overall prevalences of 9.2%–25.4% and overall microfilariae (mf) geometric mean intensities of 321–1172 mf/mL of blood. In the same villages, hydrocele affected 8.5%–27.9% of adult males (aged ⩾20 years), and 5.6%–6.6% of adult individuals had elephantiasis (mainly of the legs). In general, the patterns of filarial infection and disease in the endemic villages resembled those observed in endemic villages in the coastal part of East Africa, with the exception that in the Ghanaian focus more females than males were affected by elephantiasis. Entomological surveys revealed that Anopheles gambioe s.l. and A. funestus were vectors of filariasis in the endemic villages. Only negligible prevalences of microfilaraemia were observed in town communities located close to highly endemic villages. Control of filariasis in this area is difficult with presently available measures, and new control tools, especially development of new drug regimens for mass treatment, are greatly needed.Item Malaria infection, morbidity and transmission in two ecological zones Southern Ghana(1995-05) Afari, E.A.; Appawu, M.; Dunyo, S.; Baffoe-Wilmot, A.; Nkrumah, F.K.A one year survey was conducted in 1992 to compare malaria infection, morbidity and transmission patterns between a coastal savannah community (Prampram) and a community (Dodowa) in the forest zone in southern Ghana. The study population of 6682 at Prampram and 6558 at Dodowa were followed up in their homes once every two weeks and all episodes of clinical malaria recorded. Blood films for microscopy were prepared from 600 participants randomly selected in each community in April and in August representing dry and wet seasons respectively. Mosquitoes biting humans between 1800 hrs and 0600 hrs, as well as indoor and outdoor resting mosquitoes were collected weekly. All mosquitoes collected were classified into species and examined for sporozoites by dissection and ELISA. The incidence rate of clinical malaria was higher in Dodowa (106.6/1000 pop.) than in Prampram (68.5/1000 pop.) It was highest in < 10 year age groups in both communities. It was also higher in the wet season than in the dry season. The prevalence of patent parasitaemia at Prampram and Dodowa in April in the dry season. The prevalence of patent parasitaemia at Prampram and Dodowa in April 1992 was 19.8% (117/590) and 42.2% (253/599) respectively. The corresponding figures for August were 26.6%(160/602)at Prampram and 51.3% (309/602) at Dodowa. Plasmodium falciparum infection contributed 78-85% of the parasitaemia in April and 93-99% in August. The average man-biting rate for Anopheles gambiae s.l was higher at Prampram than at Dodowa (1.54 vs 0.79 bites/man/night) but the average sporozoite rate was higher at Dodowa than at Prampram (2% vs 0.7%). The peak of biting density at Prampram occurred in June whilst that of Dodowa occurred in November.Item Malaria vector studies in two ecological zones in southern Ghana.(African Entomology, 2001) Appawu, M.A.; Baffoe-Wilmot, A.; Afari, E.A.; Dunyo, S.; Koram, K.A.; Nkrumah, F.K.A two-year longitudinal malaria vector study was carried out in two communities, Dodowa and Prampram, located in the coastal forest and coastal savannah zones, respectively, of the Dangme West district of Ghana. Anopheles gambiae s.l. Giles was most prevalent in both study areas, followed by An. funestus Giles in Dodowa and An. pharoensis Theobald in Prampram. Anopheles gambiae s.s. occurred in sympatry with An. melas Theobald in Prampram. Small numbers of An. nili Theobald, An. hancocki Edwards, An. coustani Laveran, An. moucheti Evans and An. hargreavesi Evans were collected in Dodowa and their role in transmission was negligible. Anopheles gambiae s.l. and An. funestus were found to be the major human-biting species in Dodowa, while An. gambiae s.l. and An. pharoensis were the most common biting mosquitoes in Prampram. The overall biting rate of the anophelines at Dodowa was twice that at Prampram. Anopheles gambiae s.l. and An. funestus were identified as the main vectors of malaria by salivary gland dissections. Overall mean infectivity rate of both species was approximately 2.5 times higher at Dodowa than at Prampram. Anopheles pharoensis was not found to be infected with Plasmodium parasites. The intensity of malaria transmission at Dodowa, the coastal forest area, was about six times higher than Prampram, the coastal savanna area. Some aspects of control strategies are discussed.Item Species composition and inversion polymorphism of the anopheles gambiae complex in some sites of Ghana, West Africa.(Acta Tropica, 1994) Appawu, M.A.; Baffoe-Wilmot, A.; Afari, E.A.; Nkrumah, F.K.; Petrarca, V.Samples of Anopheles gambiae s.1. were collected from eight localities belonging to four of the five main ecological strata of Ghana. Analysis of ovarian polytene chromosomes revealed the presence of A. gambiae s.s. in all the sites studied, while A. arabiensis was detected only in the extreme northern locality of Navrongo and A. melas in some southern sites. Anopheles arabiensis showed a degree of inversion polymorphism comparable to the one observed in other West African countries. The analysis of the chromosomal polymorphism of A. gambiae s.s. showed the presence of the FOREST form in the rain forest localities and the SAVANNA form in the coastal savanna sites. The MOPTI form occurred sympatrically with the SAVANNA form in the northernmost locality. The possible influence of the presence of various taxa of the A. gambiae complex and of their intra-specific variants on malaria vectorial system is discussed.